Differential-pressure gage.



W. R. BROWN. DIFFERENTIAL PRESSURE GAGE.

APPLIOATION FILED AUG. 13, 1909.

1,001,810. "Patented Aug. 29, 1911.

STATES J ICE.

WILLIAM R. BROWN, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, To THE WATER WORKS SPECIALTY COMPANY, A CORPORATION OF SOUTH DAKOTA.

nxrrnnnnrmt-rnnsscsn GAGE.

racis thereof, and particularlyadapted-tor use in measuring the flows of liquids jby means of Pitot tubes or Venturi meter 1; to provide improved means for preventin' damage to a flexible diaphragm through ithe pressure thereon; and to provide improled and convenient means for checking o1 dalibrating the indications of the reeordin device.

A specific construction emit ydying this invention is illustrated in the,accommnying drawings, in which:

Figurejl is a schematic view of a diflerential. pressure gage, some of the parts being shownin vertical section and some diagrammatically Fig.2 is a detail of the connection between the stem of the diaphragm and the shaft which actuates the pen, the inclosing casing being shown in section.

The device shown comprises a closed casing or receptacle having a flexible, resilient diaphragm extending across its interior so as to divide it into two non-communicating compartments, a pair of pipes ortubes for respectively connecting these compartments with sources of fiuid pressure, a by-pass extending between the tubes and located at a point between the receptacle and the sources of pressure, a U-tube connected between opposite sides of the receptacle to indicate the difl'erence of pressures on opposite sides of the diaphragm, and means outside the easing for recording the movements of the diaphfagm graphically.

In the form shown, the closed receptacle comprises two parts or walls bolted together so as to grip the edges of the diaphragm.

tach of these walls is concave toward the diaphragm, the curvature of the walls being such as to correspond to the bending of the diaphragm under static fluid pressure. The curved wall 1 is cast integral with the base plate andis provided with an, aperture Specification of Letters Patent. Application'filedAugust 13, 1909.

Patented Aug. 29, 191.1. Seria1 No. 512,703.

2 preferably at its center, and the pipe connected at this point. The opposite wall 4 is also provided with an aperture 5 to which a pipe 6 is connected. A rubber valve 7 is mounted at the center of the flexible diaphragm 8, and'the walls adjacent to the inner ends of the apertures 2 and 5 are shaped to form seats for the valve 7. Bolts 9 connect the walls 1. and 4 and also secure the diaphragm 8 in place. The diaphragm 8 may be of any suitable construction but is preferably of resilient material, such as stretched rubber mounted for convenience between two stifl' annular rings 10. This arrangement permits the diaphragm to be removed or replaced without changing the tension on the material of the diaphragm.

The mechanism which'records the movement of the diaphragm comprises a stem 11 which is connected to the middle of the diaphragm and extends at right angles to the plane of the diaphragm through the pipe 3 and into a second casing 12, where its movement is communicated to an arm 13, by means of a shoulder or set pin 14 onthe stem 11. The arm 13 is mounted on the pen shaft. 15, which extends through a stuifing box 18, arranged to permit said shaft to rotate freely, while preventing the escape of liquid from the casing 12. The end of the stem 11 passes through a small aperture 16 in the wall of the casing 12, which aperture serves as a guide for the stem. A blind pipe 17, :torming an extension of the ca--i 1g 12, incloses the stem 11, and permits the same to be entirely surrounded by liquid under the same pressure as that in the main rec'eptacle at the same side of the diaphragm. The lower end of the pen shaft 15 is supported by an adjustable step bearing 19.

The pen arm 20 is rigidly mounted on the shaft 15,:and has a balance Weight 21 at one end .to counter-balance the weight of the marking-pen 22 at its other end. An adjusting screw 23 permits the pen to be adjusted verticallywith respect to the chart .or paper roll 24, upon which the recordis drawn.

The paper is movedover the support 25 by The pen arm 20 is preferably extensible so that the pen may be shiftedvtoward and away from the axis of the shaft 15 for adjustin its rate of movement with respect to that of ,the stem 11. Adjustment of the length ef the pen arm is accomplished by suitable clockwork mechanism, not shown.

means of an adjusting nut 27, which engages a threaded part of the extension26 of the arm 20. By means 01" this adjustment, the movement of the pen may be adjusted for calibrating the instrument or for multiplying the pressures by a constant quantity such as a formula co-efficient.

The chambers 28 and 2-9 at opposite sides of: the diaphragm S are connected with pipes 30 and 31 respectively which are arranged to transmit to the respective chambers the liquid pressures whose differences are to be recorded. For instance, the ends of the pipes 30 and 31 may be provided with Pitot tubes, or other means adapted to be inserted into a conduit containing a flowing liquid, and. arranged to transmit to the respective compartments the static pressure in the c0nduit, and the static pressure plus the pressure due to the velocity of the liquid.

In order to prevent injury to the diaphra gm, through sudden application of high pressure thereto the pipes 30 and 31 are con- .nected by means of a bypass 32 controlled If this valve is open when the 31 are subjected to pressure, the pressures at both sides of the diaphragm 8 will be equal, regardless of any difference of pressures at the source or sources of pressure with which the pipes 30 and 31 are connected. By gradually closing the valve 33,

by a valve 33. pipes 30 and the liquid in the chambers 28 and 29 will be gradually brought to the same pressures as those in Pitot tubes which may be connected to the respective pipes 30 and 31.

The cap 36 of the external pressure chamber 12 is arched in order to trap gas at its highest point. A small tube 37 connects this point with a hole tapped in the wall plate 1 at its highest point 38. The two high points being joined by the tube 37 have an outlet valve 39. In a similar manner the pressure chamber 28 is provided with a gas vent 40 at its highest point and a valve i1 controlling the vent. Connected with the valves 39- and &1 are two pipes 12 and 43, which support between them a glass U-tube 44:, which is provided for the purpose of holding a colcred liquid to indicate the difference in pressurcs on opposite sides of the diaphragm 8.

This colored'liquid should be one which is of greater specific gravity from thatpf which the pressure is being tested. When it is desired to use the U-tube, the, blow-oft valves 15 are closed. Valves 47 when closed/enable be blown oil at the valves 4:5 with out risk of losing the colored liquid from the U-tube. I

In addition to making the diaphragm 8 of resilient material so that it normally as- Sumes its middle position, the diaphragm is providedw'tith springs 48 which also urge it to this middle position. One of these springs is connected between the end of the stem 11 and an adjusting screw 49, and the other is located at the opposite side of the diaphragm 8 and connected between an ex-.

tension 50 and an adjusting screw 19. Both the stem 11 and its extension 50 are detachably connected ;with the diaphragm so as to permit the diaphragm to be readily removed when the two casing parts 1 ands are separated. a

The operation of the device shown is as follows: Assume for example that the appav ratus isto be used for measuring the flow of liquid in a pipe.

arranged, sure-of the liquid, and the other for indi eating the pressure flow of the liquid plus the static pressu/te'. The static pressure is usually taken by a straight nozzle which extends into the pipe For this purpose the pipes 30 and 31 are connected with suitable 1102- zles adapted tobe inserted" into the pipe=and one for indicating the static pres-j due to the velocity e f at right angles to the directionof flow of,

the liquid therein,

and the other is gin'the form of a bent nozzle or Pit'ot tube directed.

along the direction of flow of the'liquid'. In such case, the static pressure alone, while the Pitot tube the straight nozzl indicates or bent nozzle mdicates the static pressureplus the pressure due to the flow. Previous to admitting the liquid to the/casing, the bypass valve 33 is opened so asto preventdam- After the age to the flexible diaphragm 8. connections have been made, the by-pass valve 33 is gradually closed, and the resulting motion of the pen/arm case the difference impressure comes 'within the range of the flexible diaphragm, .the by-, pass valve 33 is completely closed. Inorder to secure accurate results, the valves 39 and 41 are opened long enough the pipes and spaces with the liquid under pressure, thus eliminating all bubbles of air or gas which would tend to produce misleading results, as is well known. The difference in pressure in either direction will be recorded by a movement ofthe stem con- 20 is noted. In a r to completely fill neeted to the center of the diaphragm, and

the "multiplied motion of the diaphragm through the action of the pin 1-} and the guide arms which form the link 13, cause a motion of the-flexible diaphragm 8, the valve of 7 engages the valve seat and closes one the pipes 30 or 31. In either-case, the stoppage of the flow through the pipes 30 or 31 prevents injury tot-hodiaphragm.

, The U-tube is particularly valuable for calibrating and for testingthp accuracy 0 the recording devices, and being connected at the highest part of the casing, it serves as a convenient means for enabling the operator to detect and get rid of bubbles of air that may accumulate in the chambers.

.tlthough but one specific embodiment of this invention is herein shown and described, it will be understood that numerous details of the crinstruction shown may be altered or omitted, within the scope of the following claims, without departing from the spirit of this invention.

I claim 1. In a ditterential pressure gage, the combination of a closed receptacle, a flexible diaphragm subdividing said receptacle into ,two compartn'ients, pipes connecting said (Oll'lPitl'lIDQlltS with sources of fluid pressure,

a valved by-pass connecting said compartments, mechanism for indicating the moveinents of said diaphragn'i, and means actuated by said diaphragm to automatically cutting otll communication between said receptacle and one of said pipes through the movement of the diaphragm.

2.1n a ditlferential pressure the combination of a closed receptacle, a flexible diaphragm subdividing said receptacle into two compartments, pipes onnecting said compartments with sources of fluid pressure, a valved by-pass connecting said con'ipartmeats, mechanism for indicating the movements of said diaphragm, and a valve carried by said diaphragm and adapted to cut ofi communication between said receptacle and oneof said pipes through the movement of said diaphragm.

3. In a. dill'erential pressure gage, the combination of a closed receptacle, a movable partition therein, subdividing the interior into tWo separate, non-communicating compartments, individual tubes connecting said coi'i'ipartments with sources of liquid pressiiire, means normally urging said partition to a certain middle position, said partition being movable through differences of pressures on the opposite sides thereot', a stem connected with said partition. a shoulder on said stem, a casing surroundingsaid stem, a shaft extending into said casing idjacent to said stem, an. arm carried by said shaft and adapted to have sliding engage ment with said shoulder for rotating said sha'l t. througl'i the movement of said stem, and an iudicato arm actuated by said ha it.

4. The combination of a closed receptacle, a. vertically disposed, movable diaphragm subdividing said receptacle into two compartnients, means normally urging said diaphragm to a certain middleposition. said diaphragm being arranged to move to an extent varying with the difierencc ol' pressures at the opposite sides thereof, means for automatically indicating the movements of' said naphragnna U-tube and means adapted toeonncct said :-tube with said receptacle at opposite sides of said diaphragm and adapted to contain a liquid to indicate the changes in the pressures in said receptacle.

In a differential pressure gage, the combination of a closed receptacle, a movable partition subdividing said receptacle into two compartments and adapted to be moved to an extent varying with the diflerence between th fluid pressures on opposite sides thereof, pipes connecting said compartments with sources of fluid pressure, a valved by-pass connecting said pipes to each other, and mechanism for indicating the movements of said partition, said partition being vertically disposed, a U-tube and means adapted to connect said U-tube with said receptacle at opposite sides of said partition and at the uppermost points of the respective compartments.

6. In a differential pressure gage, the com bination of a closed receptacle, a movable partition subdividing said receptacle into two compartments and adapted to be moved to an extent varying with the difference between the fluid pressures on opposite sides thereof, pipes connecting said compartn'ients with sources of fluid pressure, a valved bypass connecting said pipes to each other, mechanism for indicating the movements of said partition, a pair of pipes respectively connected to the uppermost points of the compartments at opposite sides of said partition and extending upward therefrom, a U-tube having the upper ends of its legs respectively connected to said pipes, valves controlling communication between said U- tube and receptacle, and blow-oil valves above the connections between said ti -tube and pipes.

7. in a differential pressure gage, the combination'of a closed receptacle, a movable partitionsubdividing said receptacle into two compartments and adapted to be moved to an extent varying with the ditierence between the fluid pressures on opposite sides thereof, pipes connecting said compartments with sources of fluid pressure, a. valved bypass connccting said pipes to each other. mechanism tor indieating the moven'ients of? said partition, said mechanism comprising a stem connected with said partition, av closed casing surroui'iding said stem and communicating with the adjacent compartment of said receptacle, a shaft journalcd in said casing and extending outwardly therefrom. means interposed between said shaft and stem for rotating said shat't through the movement; of said partition, and means connected with the outer part of said shaft for indicating the movements of said partition.

8. in a difl'ertaitial pressure age, the combination of a elosml receptacle, a movable' partition subdividing sail receptacle into two compartments and adapted to be moved to an extent varying with the differpartition, :1 closed casing surrounding said stem and communicating with the adjacent compartment of said receptacle, a shaft joiirnaled in said casing and extending outwardly therefrom, means interposed between said shaft and stem for rotating said shaft through the movement of said partition, an arm carried on the outer part ofasaid shaft, and an indicating instrument mounted on aid arm, said instrument being adjust-able toward and away from said shaft for calibrating the instrument.

9. In a differential pressure gage, the combination of a closed receptacle, :1 flexible and elastic diaphragm subdividing said receptacle into two compartments, pipes connecting said compartments with sources of fluid-pressure, a valved by-pass connecting said pipes, movements of said diaphragm, and means actuated. by said diaphragm for preventing injury to the diaphragm throughan excess of pressure thereon. J,

Signed at Chicago this 10th day of August 1909.

\VILLIAM RBRDIWN Witnesses EUGENE A. RUMMLER, EDWIN PHELPS.

mechanism for indicating the 

